encoder-v2: use atomic store/load for buffer switching, write barrier
encoder-v2: use atomic store/load for buffer switching, write barrier

@cdsteinkuehler: do we need a barrier in update() as well?

strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit